A standalone server always has the quickest possible response time, and is intended
for large servers that are dedicated to providing FTP service. The standalone server
provides low connection latency for dedicated servers because the standalone system never has
to be restarted. The standalone server is always running, even during off-peak hours,
waiting indefinitely for connections.

How to Start an FTP Server Using SMF

By default, the SMF service is configured to start the FTP server
using the nowait mode. If the site handles many connections, the FTP server can
also be run in standalone mode. See the in.ftpd(1M) man page for information
on additional command-line options.